Field of the Invention
This application relates to methods for assessing immunohistochemistry or immunofluorescence stained muscle tissue with digital image analysis for the purpose of evaluating muscular dystrophy disease status; and more particularly, for digital image analysis-based scoring of protein expression in muscle fibers of tissues obtained from muscular dystrophy patients.
Description of the Related Art
Muscular dystrophy categorizes a group of genetic disorders which result in disorders of the muscles in the human body. Generally speaking, muscular dystrophies are characterized by progressive weakening of skeletal muscles, while additional muscle and organ systems can be impacted during the later courses of the disease. These diseases derive from defective or non-expressed proteins involved in the functional and structural molecular components of muscle fibers. The defects in, or lack of expression of, these proteins are due to mutations in the genes that encode for the respective proteins. Two of the most common forms of muscular dystrophy are Duchenne and Becker muscular dystrophy (DMD and BMD, respectively).
DMD and BMD are rare, recessive disorders deriving from mutation of the DMD gene which encodes the dystrophin protein. The DMD gene is located on the X chromosome and, therefore, DMD and BMD are X-linked disorders that manifest predominately in the male population. In rare cases DMD and BMD are observed in females [Hoffman E P et al. Cell. 1987; 51:919-928. Emery A E, Neuromuscul Disord. 1991; 1:19-29].
DMD results from complete, or near complete, loss of the functional protein product of the DMD gene, while some protein is produced in BMD patients. Dystrophin is a large protein and provides structural stability to muscle cells [Hoffman E P et al. Cell. 1987; 51:919-928.]. The characteristic symptom of DMD and BMD patients is the progressive weakening of muscles. BMD patients, due to the production of some functional protein, generally have milder symptoms than DMD [Bushby K et al. The Lancet Neurology. 2010; 9(1):77-93].
Diagnosis of DMD, BMD and other forms of muscular dystrophy involves genetic testing for mutations in known muscular dystrophy-associated genes and assessment of creatine kinase levels. For example, mutations in the DMD gene indicate DMD and BMD disease. Immunohistochemistry (IHC) assessment of muscle biopsies from suspected patients can also be evaluated [Bushby K et al. The Lancet Neurology. 2010; 9(1):77-93]. In the instances of BMD and DMD, IHC-based evaluation of muscle tissue is performed predominately to understand disease severity, or to distinguish between DMD and BMD, rather than to provide an initial diagnosis of patients.